Fluidized bed gasification forced circulation system combining cold wall and hot wall

Abstract

The circulating system comprises a semi-water-cooled wall gasifier, a front gas conveying pipe, an adiabatic high-temperature cyclone separator, a rear gas conveying pipe, a waste heat recovery boiler, a dust remover, a dust remover ash lock, an ash cooler, an ash cooler lock hopper, an ash sending hopper and a dust returning pipeline. After reacting in the dense phase adiabatic reaction section of the semi-water-cooled wall gasifier, the reactant material enters the dilute phase radiation heat recovery section, the crude coal gas generated by the reaction is preliminarily cooled and heat is recovered in this section, at the same time, the dust is settled and separated, the large dust particles are removed by the adiabatic high-temperature cyclone separator, and then the crude coal gas enters the waste heat recovery boiler through the rear gas conveying pipe, and then enters the dust remover and is sent to the downstream water washing system; the fine particles captured by the dust remover are sent to the dust remover ash lock; the dust particles captured by the adiabatic high-temperature cyclone separator enter the ash cooler and are cooled, and then are sent to the ash cooler lock hopper; the fine dust particles in the dust remover ash lock and the dust particles in the ash cooler lock hopper are sent to the gasifier by the dust returning pipeline to continue participating in the reaction.

Description

Technical Field

[0001] This invention relates to the field of gasification technology for carbonaceous materials such as coal, biomass, and waste. Background Technology

[0002] Currently, the dust particles in the high-temperature crude gas produced by the fluidized bed gasification system are fed into the gasifier for further reaction by the pressure difference generated by the height difference of the dust accumulation. The cyclone collectors the particles, which accumulate in the return pipe to form a certain material level. When the pressure generated by the material level in the return pipe is sufficient to overcome the resistance, a self-balancing cycle of return material is achieved.

[0003] This method of material return has the following disadvantages: First, because fly ash needs to overcome certain resistance, a sufficient material level is required. As the gasification pressure increases, the required material level also increases, thus increasing the height of the gasification system framework and significantly increasing investment. Second, traditional material return uses gravity, which easily leads to bridging and blockage in the return pipe, affecting normal operation. Third, the particulate matter has a high temperature, typically reaching 700℃~1100℃, making it impossible to convey unreacted carbon-containing particles into the high-temperature reaction zone of the gasifier via pneumatic conveying. Instead, they are sent to the relatively cooler gasifier wall. Due to the insufficient temperature at the wall, these high-carbon fine particles enter the gasifier but are carried out again by the gas before they can react, resulting in inefficient material return cycles. Fourth, the gasifier, high-temperature cyclone separator, return pipe and material sealing valve are rigidly connected to form a closed loop structure. As the gasification pressure increases, the metal wall temperature also needs to increase, and the temperature difference between start-up and shutdown conditions becomes larger. This rigidly connected closed loop structure has very poor resistance to deformation caused by temperature difference changes, thus posing a safety hazard.

[0004] Chinese Patent Authorization Announcement No. CN 114479948 A, authorized on May 13, 2022, the invention patent is entitled a medium-temperature dust return system for a jet fluidized bed gasifier for coal-to-syngas production. This patent discloses a medium-temperature dust return system that sends the dust separated by a high-temperature cyclone separator to a buffer cooling tank, a lock hopper, a sending hopper and a quantitative conveyor connected in sequence thereto. The quantitative conveyor directly transports the dust to the central high-temperature jet zone. First, the dust particles are conveyed via a quantitative conveyor rather than a forced pneumatic conveying method. Without an additional power source, the feasibility of the conveying method is uncertain. Second, the buffer cooling tank uses a vertical tube sheet structure or a serpentine tube structure. The tube sheet structure is used for fluid media such as gas and liquid. Solid particles are prone to bridging and blockage in the narrow space inside the tubes or between the tubes. In the serpentine tube structure, due to the gaps between adjacent tubes, a portion of the material on the upper surface of the tubes between the tubes is almost stagnant. Prolonged stagnant flow can easily lead to material agglomeration and blockage, resulting in a decrease in heat transfer efficiency. Summary of the Invention

[0005] This invention addresses the shortcomings of current technology by setting up cooling measures such as water-cooled walls and ash coolers to reduce the temperature of dust particles collected by high-temperature cyclones. The cooled medium- and low-temperature dust particles, together with the low-temperature particles collected by the dust collector, are then transported to the high-temperature reaction zone of the gasifier using a pneumatic dense-phase conveying method.

[0006] The technical solution adopted in this invention is as follows:

[0007] A fluidized bed gasification forced circulation system combining hot and cold walls includes: a semi-water-cooled wall gasifier, a front gas transmission pipe, an adiabatic high-temperature cyclone separator, a rear gas transmission pipe, a waste heat recovery boiler, a dust collector, a dust collector ash lock, an ash cooler, an ash cooler lock hopper, an ash sending hopper, and a return ash pipeline. The high-temperature, dust-laden crude gas generated by the semi-water-cooled wall gasifier passes through the front gas pipeline, then through an adiabatic high-temperature cyclone separator to remove large dust particles, and then through the rear gas pipeline into the waste heat recovery boiler for further heat recovery and cooling. The cooled dust-laden crude gas enters the dust collector to remove fine particles and is then sent to the downstream water washing system. The fine particles collected by the dust collector are sent to the dust collector ash lock for storage. The dust particles collected by the adiabatic high-temperature cyclone separator enter the ash cooler for cooling and are then sent to the ash cooler lock hopper for storage. The ash conveying hopper transports the fine powder particles in the dust collector ash lock and the dust particles in the ash cooler lock hopper to the gasifier through the return ash pipeline via a pneumatic dense phase transport to continue participating in the reaction.

[0008] A further improvement is made to the semi-water-cooled wall gasifier, which includes: a dense-phase adiabatic reaction section, a dilute-phase radiative heat recovery section, and a steam chamber. The dense-phase adiabatic reaction section consists of a pressure-bearing steel shell lined with refractory material, where the reactants are piled up to a certain height and react. The dilute-phase radiative heat recovery section consists of a water-cooled wall cylinder formed by a pressure-bearing steel shell and steel pipes, which are concentrically installed. The high-temperature, dust-laden crude gas generated in the dense-phase adiabatic reaction section undergoes preliminary heat recovery and dust settling and separation in this section. The steam chamber is located at the bottom of the gasifier and provides the gasifying agent required for the reaction.

[0009] A further improvement is made to the dense-phase adiabatic reaction section, which includes: a hot-walled cylinder and a feed inlet for the reactants. The hot-walled cylinder is composed of a pressure-bearing steel shell lined with refractory material; the feed inlet's axis forms an angle of 35° to 75° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section, near the bottom.

[0010] A further improvement is made to the dilute phase radiative heat recovery section, which includes: an enlarged section water-cooled wall located above the transition section water-cooled wall; an expansion joint that connects and seals the transition section water-cooled wall and the enlarged section water-cooled wall; a fixed support for supporting the enlarged section water-cooled wall; a displacement guide frame evenly arranged circumferentially at different heights; a protective gas ring pipe installed in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring for isolating high-temperature crude coal gas from entering the annular cavity and supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators evenly arranged circumferentially at different heights.

[0011] A further improvement is that the transition section water-cooled wall is formed by spirally winding 1 to 8 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by a combination of both; the diameter of the large end cylinder formed by the transition section water-cooled wall is 1.2 to 1.6 times the diameter of the small end cylinder, and the cone angle is 30° to 60°.

[0012] A further improvement is that the enlarged section water-cooled wall is formed by spirally winding 1 to 8 sets of steel pipes, or by bending parallel steel pipes and connecting them with flat steel, or by a combination of both; the upper part has a conical or circular opening, and the diameter of the lower water-cooled wall forming a cylinder can be greater than, less than or equal to the diameter of the large end cylinder formed by the transition section water-cooled wall; the high-temperature dust-laden crude gas outlet can be set at the top center of the water-cooled wall, or it can be set at the upper side of the water-cooled wall cylinder. The location of the crude gas outlet needs to be determined based on the comprehensive design of the height of each piece of equipment, including the insulated high-temperature cyclone separator, ash cooler, ash cooler lock hopper, and ash conveying hopper.

[0013] A further improvement is that the protective gas ring pipe is connected to the pressure-bearing steel shell cylinder by a semi-circular annular steel pipe. Protective gas distribution holes are opened at equal intervals along the circumference of the ring pipe. The position of the ring pipe is close to the sealing ring that prevents high-temperature crude coal gas from entering the ring cavity. The protective gas in the ring cavity is an inert gas, or it can be a purified synthetic gas. The pressure of the protective gas is slightly higher than the internal pressure of the dilute phase radiative heat recovery section to achieve the purpose of positive pressure sealing.

[0014] A further improvement is made to the gas chamber, which includes: a gas distribution plate for supporting the reactants, ash return ports located on the distribution plate (the number of ash return ports can be set to 1 to 6), a gasifying agent inlet, and a slag discharge ring cavity formed by a central pipe providing an oxygen channel and a slag discharge pipe concentrically installed.

[0015] A further improvement is that the gas distribution plate is a conical gas distribution plate formed by rolling steel plates, with a cone angle in the range of 60° to 120°. Small holes for introducing gasifying agent are opened at equal intervals on the distribution plate, and the angle between the axis of the small holes and the axis of the cone of the distribution plate is in the range of 30° to 60°. A high-temperature wear-resistant heat insulation layer of 20mm to 100mm can be applied to the surface of the distribution plate in contact with the reactants.

[0016] A further improvement is that the front gas transmission pipe is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell cylinder and a steel pipe, which are installed concentrically. The front gas transmission pipe is connected to the top or upper side of the semi-water-cooled wall gasifier according to the outlet position of the high-temperature dust-containing crude gas. This includes: when connected to the top of a semi-water-cooled wall gasifier, the bottom end of the vertical gas pipe water-cooled wall is inserted into the conical or circular opening at the top of the water-cooled wall of the gasifier's expansion section; the amount of protective gas passing through is adjusted by controlling the size of the gap ring formed by the two, maintaining a stable pressure difference between the annular cavity and the inner cavity enclosed by the water-cooled wall; when connected to the upper side of a semi-water-cooled wall gasifier, the front end of the horizontal gas pipe water-cooled wall is inserted into the circular opening on the side of the water-cooled wall of the gasifier's expansion section, and the two are connected and sealed with an expansion joint; a displacement guide frame for limiting the displacement direction of the water-cooled wall; a sealing expansion joint for preventing high-temperature crude gas from entering the annular cavity and for displacement compensation; a soot blower for purging ash accumulated at the bottom of the horizontal gas pipe water-cooled wall; and a protective gas inlet for the annular cavity located near the sealing expansion joint.

[0017] A further improvement is that the water-cooled wall is formed by spirally winding 1 to 6 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by a combination of the above two methods. A 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer is applied to the side of the water-cooled wall that is in contact with the high-temperature dusty crude coal gas.

[0018] A further improvement is made to the insulated high-temperature cyclone separator, which consists of a pressure-bearing steel shell with a high-temperature wear-resistant lining and a water-cooled wall center cylinder. The water-cooled wall center cylinder is formed by spirally winding 1 to 4 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel. The surface in contact with the dust-containing crude coal gas is coated with a 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer. The bottom of the water-cooled wall center cylinder is 50 to 150 mm lower than the lower edge of the gas inlet of the cyclone separator.

[0019] A further improvement is made to the rear section of the gas transmission pipe, which is concentrically assembled from a pressure-bearing steel shell cylinder and a water-cooled wall cylinder formed by steel pipes. This includes: an upward vertical gas transmission pipe water-cooled wall, a horizontal front section gas transmission pipe water-cooled wall and a horizontal rear section gas transmission pipe water-cooled wall connected by expansion joints, a downward vertical gas transmission pipe water-cooled wall, and a protective gas inlet. The upward vertical gas transmission pipe water-cooled wall can be integrated with the central cylinder of the water-cooled wall, or it can be segmented and connected by expansion joints. At the bottom of the upward vertical gas transmission pipe water-cooled wall, a sealing expansion joint with displacement compensation (meaning it is used to absorb the thermal expansion generated by the structure) is installed to prevent high-temperature crude gas from entering the annular cavity. A soot blower is installed at the bottom of the horizontal section gas transmission pipe to purge the ash accumulated at the bottom of the horizontal section water-cooled wall. The protective gas inlet is located near the sealing expansion joint.

[0020] A further improvement is that the water-cooled wall is formed by spirally winding 1 to 6 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by a combination of the above two methods. A 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer is applied to the side of the water-cooled wall that is in contact with the high-temperature dusty crude coal gas.

[0021] If refractory material falls out inside the waste heat boiler, the debris will fall to the bottom of the cone. If the gas outlet is located at the bottom of the cone, it could easily cause blockage, creating a safety risk of system pressure buildup. Therefore, a further improvement is made: the crude gas outlet of the waste heat recovery boiler is located on the upper side of the lower cone of the waste heat recovery boiler, and an ash discharge port is located at the bottom of the cone.

[0022] A further improvement is that the dust collector can be a mechanical dust collector that relies on inertia or centrifugal force, a filtration dust collector that uses metal or non-metal filter cartridges as a form of particulate matter interception, or a dust collector that combines mechanical and filtration methods.

[0023] A further improvement is that the ash cooler is a water-cooled jacket structure with 2 to 8 concentrically installed cooling coils inside. A conical discharge baffle is installed between the dust particle outlet and the spiral coil to control the material discharge speed and achieve a mixing effect.

[0024] A further improvement is that the ash cooler hopper is a water-cooled jacket structure, which achieves continuous material conveying through flushing and depressurization, and maintains pressure stability in all parts of the system while achieving pressure isolation.

[0025] A further improvement is that the dust particles in the ash conveying hopper are metered and conveyed to the return ash pipeline by a feeder.

[0026] A further improvement is that the tail end of the ash return pipeline is a conveying gas inlet, and the outlet end is connected to the ash return port of the gasifier. The conveying gas enters from the conveying gas inlet at the tail end of the ash return pipeline, and the particulate material in the ash return pipeline is injected at high speed from the ash return port of the gasifier into the high-temperature reaction zone.

[0027] The beneficial effects of this invention are:

[0028] The fluidized bed gasification forced circulation system combining hot and cold walls improves the reaction efficiency of particulate matter entering the furnace, reduces the frame height to reduce investment, reduces downtime losses caused by ash return blockage, and improves the safety and reliability of the system. It provides a more efficient, lower-investment, and safer fluidized bed gasification technology. Attached Figure Description

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Figure 1 This is a schematic diagram of the top outlet of a fluidized bed gasification forced circulation system that combines hot and cold walls;

[0031] Figure 2 This is a schematic diagram of the side outlet of a fluidized bed gasification forced circulation system that combines hot and cold walls. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0033] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, the gasification system frame refers to the frame structure for installing equipment such as gasifiers, cyclone separators, superheated boilers, and dust collectors. This structure can be a steel structure, a concrete structure, or a combination of both.

[0037] Bridging refers to the phenomenon where particulate materials, when flowing under gravity, cannot flow normally because the interactions between particles (such as cohesion, friction, electrostatic adsorption, etc.) form localized stable structures (arches or bridges).

[0038] A displacement guide frame is a device that controls the direction of thermal expansion of structural components, ensuring that the structural components expand in a predetermined direction.

[0039] Protective gas distribution holes refer to a certain number of holes that are evenly spaced along the circumference of the ring pipe, with the purpose of distributing the gas evenly in all directions of space.

[0040] Example

[0041] like Figure 1 , Figure 2As shown, a fluidized bed gasification forced circulation system combining hot and cold walls includes: a semi-water-cooled wall gasifier 001, a front gas transmission pipe 002, an adiabatic high-temperature cyclone separator 003, a rear gas transmission pipe 004, a waste heat recovery boiler 005, a dust collector 006, a dust collector ash lock 007, an ash cooler 008, an ash cooler lock hopper 009, an ash sending hopper 010, and a return ash pipeline 103. The semi-water-cooled wall gasifier 001 generates high-temperature dust-laden crude gas. After passing through the front gas transmission pipe 002, it passes through the insulated high-temperature cyclone separator 003 to remove large dust particles, and then enters the waste heat recovery boiler 005 through the rear gas transmission pipe 004 for further heat recovery and cooling. The cooled dust-laden crude gas enters the dust collector 006 to remove fine particles and is then sent to the downstream water washing system from the crude gas outlet 061. The fine particles collected by the dust collector 006 are sent to the dust collector ash lock 007 for storage. The dust particles collected by the insulated high-temperature cyclone separator 003 enter the ash cooler 008 for cooling and are then sent to the ash cooler lock hopper 009 for storage. The ash sending hopper 010 transports the fine particles in the dust collector ash lock 007 and the large dust particles in the ash cooler lock hopper 009 to the gasifier through the return ash pipeline 103 via a pneumatic dense phase transport to continue participating in the reaction.

[0042] The semi-water-cooled wall gasifier 001 mainly consists of a dense-phase adiabatic reaction section 011, a dilute-phase radiative heat recovery section 012, and a steam chamber 013. The dense-phase adiabatic reaction section 011 is composed of a pressure-bearing steel shell lined with refractory material. After the reactants are piled to a certain height, a fluidized-boiling reaction occurs in this section. The dilute-phase radiative heat recovery section 012 is composed of a water-cooled wall cylinder concentrically installed with a pressure-bearing steel shell and steel pipes. The high-temperature, dust-laden crude gas generated in the dense-phase adiabatic reaction section 011 undergoes preliminary heat recovery and dust settling separation in this section. The steam chamber 013 is located at the bottom of the gasifier and provides the gasifying agent required for the reaction.

[0043] like Figure 1 , Figure 2 As shown, the dense-phase adiabatic reaction section 011 includes: a hot-wall cylinder 112 and a feed inlet 111 for the reactants. The hot-wall cylinder 112 is composed of a pressure-bearing steel shell lined with refractory material; the feed inlet 111 has an axis that forms an angle of 35° to 75° with the horizontal plane and is located in the lower part of the dense-phase adiabatic reaction section near the bottom.

[0044] like Figure 1 , Figure 2As shown, the further improvement is that the dilute phase radiative heat recovery section 012 includes: an enlarged section water-cooled wall 122 located above the transition section water-cooled wall 121; an expansion joint 123 connecting and sealing the transition section water-cooled wall 121 and the enlarged section water-cooled wall 122; a fixed support 124 for supporting the enlarged section water-cooled wall 122; a displacement guide frame 125 arranged evenly in the circumference along different heights; a protective gas ring pipe 126 set in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring 127 for isolating high-temperature crude coal gas from entering the annular cavity and supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators 128 arranged evenly in the circumference along different heights.

[0045] A further improvement is that the transition section water-cooled wall 121 is formed by spirally winding 1 to 8 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by a combination of the above two methods; the diameter of the large end cylinder formed by the transition section water-cooled wall 121 is 1.2 to 1.6 times the diameter of the small end cylinder, and the cone angle is 30° to 60°.

[0046] A further improvement is that the enlarged water-cooled wall 122 is formed by spirally winding 1 to 8 sets of steel pipes, or by bending parallel steel pipes and connecting them with flat steel, or a combination of both; the upper part has a conical or circular opening, and the diameter of the lower water-cooled wall forming a cylinder can be greater than, less than, or equal to the diameter of the large-end cylinder formed by the transition section water-cooled wall; for example... Figure 1 As shown, the high-temperature, dust-laden crude gas outlet can be located at the center of the top of the water-cooled wall; as... Figure 2 As shown, it can also be set at the upper part of the side of the water-cooled wall cylinder. The setting of the crude gas outlet position needs to be determined according to the height design of each piece of equipment, including the insulated high-temperature cyclone separator, ash cooler, ash cooler lock hopper and ash sending hopper.

[0047] A further improvement is that the protective gas ring pipe 126 is connected to the pressure-bearing steel shell cylinder by a semi-circular annular steel pipe. Protective gas distribution holes are opened at equal intervals along the circumference of the ring pipe. The position of the ring pipe is close to the sealing ring that prevents high-temperature crude coal gas from entering the annular cavity. The protective gas in the annular cavity is an inert gas, or it can be a purified synthetic gas. The pressure of the protective gas is slightly higher than the internal pressure of the dilute phase radiative heat recovery section 012 to achieve the purpose of positive pressure sealing.

[0048] like Figure 1 , Figure 2 As shown, the steam chamber 013 includes: a gas distribution plate 131 for supporting the reactants, an ash return port 136 located on the gas distribution plate (the number of ash return ports can be set to 1 to 6), a gasifying agent inlet 132, and a slag discharge ring cavity 135 formed by the concentric installation of a central pipe 134 providing an oxygen channel and a slag discharge pipe 133.

[0049] A further improvement is that the gas distribution plate 131 is a conical shell formed by rolling steel plate, with a cone angle in the range of 60° to 120°. Small holes for gasifying agent are opened at equal intervals on the distribution plate, and the angle between the axis of the small hole and the axis of the cone of the distribution plate is in the range of 30° to 60°. A high-temperature wear-resistant heat insulation layer of 20mm to 100mm can be applied to the surface of the gas distribution plate in contact with the reactants.

[0050] The aforementioned front-end gas transmission pipe 002 is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell and steel pipes, which are concentrically installed. The front-end gas transmission pipe is connected to the top or upper side of the semi-water-cooled wall gasifier 001, depending on the outlet location of the high-temperature, dust-laden crude gas. For example... Figure 1 As shown, when connected to the top of the semi-water-cooled wall gasifier 001, the bottom end of the vertical gas supply pipe water-cooled wall 021 is inserted into the conical or circular constriction at the upper part of the water-cooled wall 122 of the gasifier expansion section. The amount of protective gas passing through is adjusted by controlling the size of the gap ring formed by the two, maintaining a stable pressure difference between the ring cavity and the inner cavity enclosed by the water-cooled wall; as shown Figure 2 As shown, when connected to the upper side of the semi-water-cooled wall gasifier 001, the front end of the horizontal gas transmission pipe water-cooled wall 022 is inserted into the circular opening on the side of the water-cooled wall of the gasifier expansion section, and the two are connected and sealed with an expansion joint; the front gas transmission pipe 002 also includes: a displacement guide frame 023 for limiting the displacement direction of the water-cooled wall; a sealing expansion joint 024 for isolating high-temperature crude gas from entering the annular cavity and having a displacement compensation function; a soot blower 025 for blowing away the ash accumulated in the lower part of the horizontal gas transmission pipe water-cooled wall; and a protective gas inlet 026 for the annular cavity is set near the sealing expansion joint.

[0051] A further improvement is that the water-cooled wall of the front gas transmission pipe 002 is formed by spirally winding 1 to 6 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by a combination of the above two methods. A 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer is laid on the side of the water-cooled wall that is in contact with the high-temperature dusty crude gas.

[0052] like Figure 1 , Figure 2 As shown, the insulated high-temperature cyclone separator 003 consists of a pressure-bearing steel shell with a high-temperature wear-resistant lining and a water-cooled wall central cylinder 031. The water-cooled wall central cylinder is formed by spirally winding 1 to 4 sets of steel pipes, or by bending parallel steel pipes and connecting them with flat steel, or a combination of both. The surface of the water-cooled wall central cylinder in contact with the dust-laden crude gas is coated with a 10 to 50 mm thick wear-resistant layer with high temperature resistance and high thermal conductivity. The bottom of the water-cooled wall central cylinder 031 is 50 to 150 mm below the lower edge of the gas inlet 032 of the cyclone separator. Otherwise, if the gap is less than 50 mm, airflow short-circuiting is likely to occur, and the solids will escape before the gas and solids can be separated; if the gap is greater than 150 mm, secondary entrainment is likely to occur, and the separated solids will be carried away by the rising airflow, while the cyclone resistance will also increase.

[0053] like Figure 1 , Figure 2 As shown, the rear section gas transmission pipe 004 is composed of a water-cooled wall cylinder formed by a pressure-bearing steel shell and steel pipes, which are concentrically installed. It includes: an upward vertical gas transmission pipe water-cooled wall 041, a horizontal front section gas transmission pipe water-cooled wall 042 and a horizontal rear section gas transmission pipe water-cooled wall 043 connected by expansion joints, a downward vertical gas transmission pipe water-cooled wall 044, and a protective gas inlet 045. The upward vertical gas transmission pipe water-cooled wall 041 can be integrated with the water-cooled wall center cylinder 031, or it can be connected in sections by expansion joints. At the bottom of the upward vertical gas transmission pipe water-cooled wall 041, a sealing expansion joint 046 with displacement compensation function is provided to prevent high-temperature crude gas from entering the annular cavity. At the bottom of the horizontal section gas transmission pipe, a soot blower 047 is provided for blowing away the ash accumulated at the bottom of the horizontal section water-cooled wall. The protective gas inlet 045 is located near the sealing expansion joint.

[0054] A further improvement is that the water-cooled wall of the rear gas transmission pipe 004 is formed by spirally winding 1 to 6 sets of steel pipes, or by bending steel pipes in parallel and connecting them with flat steel, or by combining them. A 10 to 50 mm high-temperature resistant and high thermal conductivity wear-resistant layer is laid on the side of the water-cooled wall that is in contact with the high-temperature dusty crude gas.

[0055] If refractory material detaches from the waste heat boiler, the debris will fall to the bottom of the cone. If the gas outlet is located at the bottom of the cone, it could easily cause blockage, creating a risk of system pressure buildup. Therefore, if... Figure 1 , Figure 2 As shown, the crude gas outlet 051 of the waste heat recovery boiler 005 is located on the upper side of the lower cone of the waste heat recovery boiler, and the ash discharge port 052 is provided at the bottom of the cone.

[0056] like Figure 1 , Figure 2 As shown, the dust collector 006 can be a mechanical dust collector relying on inertia or centrifugal force, a filtration dust collector using metal or non-metal filter cartridges as particulate matter interception, or a combination of mechanical and filtration dust collectors. The filtered clean crude coal gas is sent to the downstream subsequent system from the coal gas outlet 061.

[0057] like Figure 1 , Figure 2 As shown, the dust collector ash lock 007 achieves continuous material conveying through flushing and depressurization, maintaining pressure stability in all parts of the system while achieving pressure isolation. Figure 1 , Figure 2 As shown, the ash cooler 008 is a water-cooled jacket structure with 2 to 4 concentrically installed cooling coils inside. A conical discharge baffle is set between the dust particle outlet and the spiral coil to control the material discharge speed and achieve mixing.

[0058] like Figure 1 , Figure 2 As shown, the ash cooler lock hopper 009 is a water-cooled jacket structure, which realizes continuous material conveying through flushing and depressurization, and maintains pressure stability in all parts of the system while achieving pressure isolation.

[0059] A further improvement is that the dust particles in the ash sending hopper 010 are metered and transported to the return ash pipeline by the feeder 101.

[0060] like Figure 1 , Figure 2 As shown, the tail end of the return powder pipeline 103 is a conveying gas inlet 102, and the outlet end is connected to the ash return port 136 of the gasifier. The conveying gas enters from the conveying gas inlet 102 at the tail end of the ash return pipeline, and the particulate material in the ash return pipeline is injected at high speed from the ash return port of the gasifier into the high-temperature reaction zone.

[0061] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A fluidized bed gasification forced circulation system combining hot and cold walls, comprising: The system comprises a gasifier, a front-end gas transmission pipe, a cyclone separator, a rear-end gas transmission pipe, a waste heat recovery boiler, and a dust collector. The system further includes a dust collector ash lock, an ash cooler, an ash cooler lock hopper, an ash sending hopper, a return ash pipeline, and a conveying gas inlet.

2. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The cyclone separator is a hot-wall separator; the front gas delivery pipe and the rear gas delivery pipe are cold-wall gas delivery pipes.

3. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The crude coal gas generated by the gasifier enters the separator after passing through the front gas transmission pipe, and then enters the waste heat recovery boiler for cooling through the rear gas transmission pipe. After cooling, it enters the dust collector and is then output to the downstream system.

4. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The dust particles separated by the separator enter the ash cooler for cooling and then enter the ash cooler lock hopper; the dust particles collected by the dust collector are sent to the dust collector ash lock; the dust particles in the ash cooler lock hopper and the dust collector ash lock are sent to the ash sending hopper.

5. The fluidized bed gasification forced circulation system combining hot and cold walls according to any one of claims 1-4, characterized in that, The gasifier is a semi-cold-wall gasifier; the ash conveying hopper transports fine dust particles from the dust collector's ash lock and large dust particles from the ash cooler's lock hopper to the gasifier via a pneumatic dense phase conveying pipeline.

6. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The dust cooler is a water-cooled jacket structure with 2-4 concentrically installed cooling coils inside, and a conical discharge baffle is installed between the dust particle outlet and the cooling coils.

7. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The ash cooler lock hopper is a water-cooled jacket structure, which achieves continuous material conveying through flushing and depressurization.

8. The fluidized bed gasification forced circulation system combining hot and cold walls according to claim 1, characterized in that, The tail end of the return powder pipeline is the conveying gas inlet, and the outlet end is connected to the ash return port of the gasifier. The conveying gas enters from the conveying gas inlet at the tail end of the ash return pipeline, and the particulate material in the ash return pipeline is injected at high speed from the ash return port of the gasifier into the high-temperature reaction zone at the bottom of the gasifier.

9. A semi-cold-wall gasifier, comprising: The gasifier comprises a dense-phase adiabatic reaction section, a dilute-phase radiative heat recovery section, and a steam chamber. The dense-phase adiabatic reaction section includes a hot-walled cylinder and a feed inlet; the dilute-phase radiative heat recovery section is composed of a water-cooled wall cylinder concentrically installed with a pressure-bearing steel shell and steel pipes; the steam chamber is located at the bottom of the gasifier and provides the gasifying agent required for the reaction.

10. The semi-cold-wall gasifier according to claim 9, characterized in that, The hot wall cylinder is composed of a pressure-bearing steel shell lined with refractory material; the feed inlet axis is at an angle of 35-75 degrees to the horizontal plane and is located in the lower part of the dense phase adiabatic reaction section near the bottom.

11. The semi-cold-wall gasifier according to claim 9, characterized in that, The dilute phase radiative heat recovery section includes: an enlarged section water-cooled wall located above the transition section water-cooled wall; an expansion joint connecting and sealing the transition section water-cooled wall and the enlarged section water-cooled wall; a fixed support for supporting the enlarged section water-cooled wall; displacement guide frames arranged evenly along the circumference at different heights; a protective gas ring pipe installed in the annular cavity between the water-cooled wall and the pressure-bearing steel shell; a sealing ring used to prevent high-temperature crude gas from entering the annular cavity and also supporting the transition section water-cooled wall; and water-cooled wall ash removal vibrators arranged evenly along the circumference at different heights.

12. The semi-cold-wall gasifier according to claim 11, characterized in that, The protective gas ring pipe is connected to the pressure-bearing steel shell by a semi-circular annular steel pipe. Protective gas distribution holes are opened at equal intervals along the circumference of the ring pipe, and the ring pipe is located close to the sealing ring. The protective gas in the annular cavity is an inert gas or a purified synthetic gas. The pressure of the protective gas is higher than the internal pressure of the dilute phase radiative heat recovery section.

13. The semi-cold-wall gasifier according to claim 9, characterized in that, The steam chamber includes a gas distribution plate, an ash return port located on the distribution plate, a gasifying agent inlet, and a slag-falling ring cavity formed by a central pipe providing an oxygen channel and a slag discharge pipe concentrically installed; the number of ash return ports can be set to 1-6.

14. The semi-cold-wall gasifier according to claim 13, characterized in that, The gas distribution plate is a conical shell shape formed by rolling steel plate, with a cone angle in the range of 60 degrees to 120 degrees. Small holes for gasifying agent are opened at equal intervals on the gas distribution plate, and the angle between the axis of the small hole and the axis of the conical body of the gas distribution plate is in the range of 30 degrees to 60 degrees. A high-temperature wear-resistant heat insulation layer with a thickness of 20 mm to 100 mm is applied to the surface of the gas distribution plate on the side in contact with the reactants.

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